Biosensor May Detect Early Signs of Heart Attack

Originally Published MDDI July 2003

R&D DIGEST

Early detection has long been viewed as a key to limiting the consequences of heart attacks. For example, the human body undergoes significant biochemical activity long before the physical symptoms of a heart attack begin. As blood flow decreases and cardiac tissue deadens, cells release natural chemicals, such as troponins. These chemicals can act as clear and specific chemical markers that indicate a heart attack is imminent.

Research currently being conducted at the University of Missouri–Columbia (MU; Columbia, MO) could yield implantable biosensors capable of monitoring the release of troponin. Such biosensors could detect a heart attack before a person experiences physical symptoms, researchers say.

"Several studies show that heart attack patients who get to a hospital quickly have a higher survival rate and less chance of massive damage to the heart muscle," says Sheila Grant, PhD, assistant professor of biological engineering at MU and leader of the research team.

Grant's team is developing biosensors for two types of deployment. One device, a glass disk that is approximately 1 cm², can be implanted under the skin's surface. A second device is an optical fiber designed to be inserted into blood vessels near the heart. Grant suggests that this sensor can be coupled with a pacemaker. The device has had great success in sensing troponins in the lab setting, she adds. But designing a sensor that is compatible with the chemistry of the human body is more problematic. "The sensing capability is there," Grant says. "We've already shown that we can sense troponins in the laboratory. The biocompatibility issue is much more complex. We have to try to fool the body into accepting this foreign material."

To accomplish this, the researchers must coat the sensors with a material that will allow them to integrate with surrounding tissue. In short, fibrous tissue must be prevented from encapsulating sensors and rendering them ineffective. One team member is investigating methods that can be used to immobilize detecting antibodies to the surface of the optical fiber while preventing tissue encapsulation.

Grant's research is funded by a private medical device company that hopes to produce a biosensor for medical use. The team has received approval to test the sensors in clinical trials with rats but predicts it will take three to five years before human clinical trials can be established.

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